The 25-year-old, whose outings in amber and black have been fleeting to date, has joined Trinity until January 22 initially and goes straight into their squad for Tuesday's home fixture against league leaders Scarborough Athletic.
Margetts has been granted permission to feature in the Buildbase FA Trophy, with Trinity entertaining Tamworth at the weekend, but will not be able to play should the Blues draw the Pilgrims in a later round.